1. Field of the Invention
This invention provides a convenient method for preparing 4-trichloromethoxybenzoyl chloride by the direct chlorination of 4-methoxybenzoyl chloride, without the use of either a chlorination catalyst or radical initiators. The product is useful as an intermediate for the synthesis of other organic compounds.
2. State of the Art
L. M. Yagupol'skii, Doklady Akad. Nauk S.S.S.R. 105, 100-102 (1955) taught the synthesis of 4-trichloromethoxybenzoyl chloride by the chlorination in the presence of phosphorus pentachloride of 4-methoxybenzoyl chloride. The same compound was also prepared by Hempel and Klauke, U.S. Pat. No. 3,935,258, using chlorination in the presence of a radical-forming agent, such as ultraviolet light or a peroxide.
An article by Louw and Franken, Chem. and Ind. 127 (Feb. 5, 1977) is also important to the background of this invention. The article shows that chlorination of methoxybenzene gives predominately ring-chlorination, not side-chain chlorination, but that methoxybenzene is chlorinated on the methoxy group with the assistance of ultraviolet light to create free-radical conditions.